For several years now, rumours have been circulating through emails and on blogs that the planet Mars is currently undergoing an exceptionally close approach to the planet Earth, at the closest point of which it will be as large in our night sky as the Moon. This approach is further said to be a relatively rare event, with the next one happening in the 23rd century (specifically 2287). Interestingly enough, the same rumour has been circulated each year, absent the date reference: thus, there have been claims that Mars will make this unusually close approach on August 27, 2010, August 27, 2007, and so on.
“The red planet is about to be spectacular,” announces the typical notice about this supposedly upcoming astronomical event. Mars will, the more extreme version of the message goes on, pass closer to Earth than it ever has “in recorded history.” Other messages are more sanguine, saying only that Mars will pass within about 35 million miles of the Earth and that this will not happen again until the 23rd century. (Incidentally, if something happens about every 280 years, then it would have already happened numerous times in recorded history.)
This same message has been sent out, and then debunked, on a more or less annual basis: here, for example, are discussions of what NASA calls the “Mars hoax” in 2005, 2007, and 2010. One assumes that each year a new batch are taken in by the hoax, and therefore that a smaller population will be deceived each year until this one finally fades away entirely.
In the meantime, let’s be clear on something: Mars will never be so close to the Earth to rival our Moon in the night sky. On the off-chance that this does happen perhaps a couple of billion years in the future, it will be because the cramped orbits in the inner solar system have finally lost out to chaos, and the planets are on collision courses with each other.
Barring that unlikely event in the distant future, Mars and Earth have regular, well-defined orbits and, while they are closer at times than at others, they are never so close that Mars is as large or as bright as our own Moon. It does indeed close in to nearly 35 million miles distance on occasion – and, several years ago, NASA estimated that it really was closer than at any other time in recorded history. Even at that time, however, it was a faint pinprick of light compared to the Moon.
Even if Mars closed within 35 million miles of Earth, at the closest point in its pass, this would still be orders of magnitude farther away than the Moon, which is about a quarter-million miles away. Mars is over twice the size of the Moon, so it would still have a long, long way to go before it was as bright as the Moon in the night sky.